1. Field of the Invention
The invention relates to a membrane welding machine having a nozzle for directing discrete streams of air along separated and parallel first and second paths, and is directed more particularly to a weld wheel assembly for a machine for heat welding two overlapping roof and/or waterproofing membranes to each other.
2. Description of the Prior Art
It is known to provide a device for heat welding two overlapping roof membranes to each other, and to provide such device with a nozzle for directing discrete streams of fluid along separated and parallel first and second weld paths. See, for example, U.S. Pat. No. 4,834,828, issued May 28, 1989, to Colin R. R. Murphy.
The Murphy patent relates to a machine for effecting continuous heat welds on either side of a fastener means, such as a row of fasteners, or an elongated bar. To effect the parallel welds simultaneously, the Murphy machine is provided with a nozzle which directs a stream of hot air to generally parallel paths on both sides of the fastener means. The upper overlapping membrane is heat sealed to the lower overlapped membrane along the overlap portion to seal the two membranes together on either side of the fastener means. The fastener means fastens the lower membrane to an uppermost hard surface of a roof, and is, in turn, covered by the upper membrane. To effect the two welds simultaneously, the nozzle is essentially a bifurcated nozzle which is moved by the machine between the two membranes, under an edge of the upper membrane.
The Murphy nozzle is provided with two outlets substantially side-by-side and in substantially the same plane, heightwise. The two outlets are separated by a bridge portion which connects the two outlets and channels hot air thereto. It has been found that the nozzle arrangement is not entirely satisfactory in that the closeness of the two welding locations causes one to adversely influence the other. It has been found that air flows vary in intensity and temperature due to nozzle design. Further, hot air from one nozzle outlet crosses over to the area impacted by the other nozzle outlet and causes bubbling or rippling of the upper membrane on the lower membrane. It has further been found that the two outlets, being in substantially the same plane, both tend to drag along the surface of the lower membrane and cause the nozzle bridge portion, i.e., the nozzle portion between the two outlets, to move along the fastener means with insufficient clearance. Still further, because the Murphy nozzle outlets are in the same vertical plane, and weld simultaneously, the membranes tend to move, causing wrinkles. When the fastener means comprises a row of discrete fasteners or elements, the nozzle bridge portion is bounced upwardly upon encountering a fastener or element, causing the nozzle outlets to rise momentarily, effecting a non-welding segment in both weld paths and potentially creating xe2x80x9cfishmouthsxe2x80x9d in seams. The Murphy nozzle, when inserted into the membrane overlays, is locked into position and cannot accommodate irregularities in the substrate without diminishing seam quality.
There is thus a need for an improved nozzle of the type described above, but in which the welds are effected concurrently but at points removed from each other such that one weld contributes to another, rather than detracting from the other, and in which the welds are effected continuously and free from interruptions caused by collisions with the fastener means.
It is, therefore, an object of the invention to provide an improved nozzle for directing discrete streams of hot air along separated and parallel first and second paths.
A further object of the invention is to provide an improved nozzle for a device for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping membranes.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a nozzle for directing discrete streams of fluid along separated and generally parallel first and second paths. The nozzle comprises a chamber for receiving air of a selected temperature, a first outlet arm extending from the chamber and having a first outlet at a distal end thereof and in a first outlet plane, and a second outlet arm extending from the chamber and having a first portion adjoining the chamber and having an axis transverse to an axis of the first outlet arm, and having a second portion with a second outlet at a distal end thereof and in a second outlet plane, an axis of the second portion being generally parallel with the axis of the first outlet arm, the second outlet plane being offset from the first outlet plane.
In accordance with a further feature of the invention, there is provided a nozzle for a device for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping roof membranes, and the nozzle is mounted on the device and adapted to effect heat welds to the roof membranes on both sides of, and adjacent to, the fastener means. The nozzle comprises a tubular body defining a chamber for receiving heated air, a first outlet arm extending from the body and having a first outlet at a distal end thereof, a second outlet arm extending from the body and having a first portion adjoining the chamber and having an axis transverse to an axis of the first outlet arm, and having a second portion with a second outlet at a distal end thereof, an axis of the second portion being generally parallel with the axis of the first outlet arm. The second outlet arm first portion is recessed on an underside thereof so as to permit the fastener means to pass therethrough as the device and the nozzle move along the paths.
In accordance with a further feature of the invention, there is provided a roof membrane welding assembly for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping roof membranes, the assembly being mounted on a device adapted to effect heat welds to the roof membrane on both sides of, and adjacent to, the fastener means. The welding assembly comprises a nozzle provided with a chamber for receiving heated air, a first outlet arm extending from the chamber and having a first outlet at a distal end thereof, a second outlet arm extending from the chamber and having a second outlet at a distal end thereof, the first outlet being disposed in a first plane, and the second outlet being disposed in a second plane removed from the first outlet plane. A first weld wheel is mounted on the device adjacent to, and in operation immediately following, the nozzle first outlet. A second weld wheel is mounted on the device adjacent to, and in operation immediately following, the nozzle second outlet. One of the weld wheels is biased by biasing structure on the device toward the roof membrane in operation of the device.
In accordance with a still further feature of the invention there is provided a weld wheel assembly for disposition on a roof membrane welding machine and for positioning a weld wheel adjacent a nozzle hot air outlet for pressing an overlying roof membrane heated by the nozzle against an underlying roof membrane heated by the nozzle, for welding the membranes together. The assembly comprises a weld wheel rotatably mounted on an axle which is moveable toward and away from the membranes, and pressure exerting structure mounted on the device and operable to bias the axle toward the membranes during operation of the machine.
The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.